On 2024/05/16 2:01, Dmitry Osipenko wrote:
On 5/15/24 19:42, Akihiko Odaki wrote:
It may be better to actually implement unmapping instead of returning an
error for consistency with the iov operation. Apparently crosvm also
unmaps blobs with VIRTIO_GPU_CMD_RESOURCE_UNREF.
Then I'll add back `async_unmap_in_progress` because resource can be
both mapped/unmapped on unref, and we'll need flag to know whether async
unmapping has been finished to do the final unmapping of the resource.
Such a situation should be already handled since unmapping in progress
blocks all commands (not just VIRTIO_GPU_CMD_RESOURCE_UNMAP_BLOB but
literally all, including VIRTIO_GPU_CMD_RESOURCE_UNREF).
The async unmapping consists of 3 parts:
1. begin async unmapping with memory_region_del_subregion() and suspend
2. wait for res->mr to be freed and resume
3. finish the unmapping with final virgl_renderer_resource_unmap()
Parts 1 and 3 are handled by virtio_gpu_virgl_async_unmap_resource_blob()
The VIRTIO_GPU_CMD_RESOURCE_UNMAP_BLOB is different because we know that
blob is mapped in the first place. Hence we can safely perform the part
3, assuming that parts 1/2 has been completed.
In case of VIRTIO_GPU_CMD_RESOURCE_UNREF, blob can be unmapped in the
first place and we can't do the part 3 because it will error out for
unmapped resource since parts 1/2 were not performed.
VIRTIO_GPU_CMD_RESOURCE_UNREF should also call
virtio_gpu_virgl_async_unmap_resource_blob(). I guess that's the
original intention of having a function for this instead of inlining the
content of this function to virgl_cmd_resource_unmap_blob().
